Is climate change real?

Yes, climate change is real. The Earth’s climate is warming at an unprecedented rate in human history, and human activities—primarily the emission of greenhouse gases like carbon dioxide (CO₂) from burning fossil fuels—are the dominant cause. This is supported by overwhelming evidence from multiple independent lines of observation and analysis, and by a near-unanimous scientific consensus.[1]

Scientific Consensus

•Multiple studies of peer-reviewed literature and surveys of climate scientists show extremely high agreement. Classic analyses found ~97% consensus that humans are causing global warming; more recent reviews of tens of thousands of papers find greater than 99% (in some cases >99.9%) agreement on human-caused climate change.[2]

•Leading scientific organizations worldwide—including NASA, NOAA, the IPCC (Intergovernmental Panel on Climate Change), the National Academies of Sciences, the American Meteorological Society, the American Association for the Advancement of Science, and others—have issued clear statements affirming this. The IPCC states it is “unequivocal” that human influence has warmed the atmosphere, ocean, and land.[3]

•There is no significant disagreement among actively publishing climate experts on the core facts of warming and its primary human cause. Debates exist on details like exact future projections, regional impacts, or optimal policy responses, which is normal in science.

Key Evidence That Earth Is Warming

•Global temperature rise: Independent datasets (NASA GISS, NOAA, UK Hadley Centre, and others) show the planet’s average surface temperature has risen by approximately 1.1°C (about 2°F) since the late 19th/pre-industrial period (1850–1900 baseline), with most warming since the mid-20th century. Recent decades and years have been the warmest in the instrumental record.[4]

•Oceans and cryosphere: Oceans have absorbed most of the excess heat; sea levels are rising; Arctic sea ice is declining in extent and thickness; Greenland and Antarctic ice sheets are losing mass (hundreds of billions of tons per year); glaciers are retreating worldwide; and snow cover is decreasing in the Northern Hemisphere.[5]

•Other indicators: Shifts in plant/animal ranges and timing (e.g., earlier blooming, species moving poleward), increases in heat extremes, changes in precipitation patterns, and more. Paleoclimate data (ice cores, tree rings, sediments) confirm the current rate of warming is unusually rapid compared to natural changes over millennia.[6]

Evidence That Humans Are the Main Cause

•Greenhouse gas increase: Atmospheric CO₂ has risen from ~280 ppm pre-industrial to over 420 ppm recently (e.g., global averages around 422–427 ppm in recent years, with record highs continuing). Methane and nitrous oxide have also increased substantially. This is directly measured (e.g., Mauna Loa record since the 1950s) and confirmed by ice-core data showing levels higher than at any point in at least the last 800,000 years. The isotopic “fingerprint” and rapid rise match fossil fuel burning and land-use changes, not natural sources like volcanoes.[7]

•Physics of the greenhouse effect: CO₂ and other GHGs trap heat. Basic radiative physics, lab measurements, satellite observations of outgoing radiation, and climate models all confirm that rising GHGs cause warming. No other known factors (solar output, volcanoes, orbital cycles, etc.) can explain the observed pattern and magnitude of recent warming.[8]

•Attribution studies (“fingerprinting”): The spatial and temporal patterns of warming (troposphere warming + stratosphere cooling, greater land than ocean warming, etc.) match human GHG forcing and rule out natural alternatives. IPCC and other assessments conclude human activities caused virtually all the warming since the mid-20th century (best estimates around 1°C or more of human-induced warming).[9]

Natural climate variability (e.g., El Niño, volcanic eruptions, solar cycles) occurs and influences year-to-year or decade-to-decade fluctuations, but it does not account for the long-term upward trend. Earth’s climate has changed naturally in the distant past (ice ages, etc.), but the current changes are happening much faster and are driven by human emissions.

In short, the reality of climate change and its human cause rest on robust, multi-decadal, multi-method evidence that has only strengthened over time. For primary sources, see NASA’s climate pages, NOAA Climate.gov, IPCC Assessment Reports (especially AR6), and peer-reviewed literature.

Citations (9)

1archive.isData and tools
https://archive.is/2025.02.12-121037/https://science.nasa.gov/climate-change/faq/do-scientists-agree-on-climate-change/
Backs: “This is supported by overwhelming evidence from multiple independent lines of observation and analysis, and by a near-unanimous scientific consensus.”
2iop.orgAcademic
https://iopscience.iop.org/article/10.1088/1748-9326/ac2966
Backs: “Classic analyses found ~97% consensus that humans are causing global warming; more recent reviews of tens of thousands of papers find greater than 99% (in some cases >99.9%) agreement on human-caused climate change.”
3climate.govGovernment
https://www.climate.gov/news-features/climate-qa/isnt-there-lot-disagreement-among-climate-scientists-about-global-warming
Backs: “The IPCC states it is “unequivocal” that human influence has warmed the atmosphere, ocean, and land.”
4climate.govGovernment
https://www.climate.gov/news-features/climate-qa/what-evidence-exists-earth-warming-and-humans-are-main-cause
Backs: “Recent decades and years have been the warmest in the instrumental record.”
5archive.mdData and tools
https://archive.md/2024.03.26-131437/https://science.nasa.gov/climate-change/evidence/
Backs: “Greenland and Antarctic ice sheets are losing mass (hundreds of billions of tons per year); glaciers are retreating worldwide; and snow cover is decreasing in the Northern Hemisphere.”
6nasa.govGovernment
https://science.nasa.gov/climate-change/evidence/
Backs: “Paleoclimate data (ice cores, tree rings, sediments) confirm the current rate of warming is unusually rapid compared to natural changes over millennia.”
7climate.govGovernment
https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide
Backs: “The isotopic “fingerprint” and rapid rise match fossil fuel burning and land-use changes, not natural sources like volcanoes.”
8royalsociety.orgAcademic
https://royalsociety.org/topics-policy/projects/climate-change-evidence-causes/basics-of-climate-change/
Backs: “No other known factors (solar output, volcanoes, orbital cycles, etc.) can explain the observed pattern and magnitude of recent warming.”
9ipcc.chGovernment
https://www.ipcc.ch/report/ar6/syr/longer-report
Backs: “IPCC and other assessments conclude human activities caused virtually all the warming since the mid-20th century (best estimates around 1°C or more of human-induced warming).”